This project comprises a detailed investigation of a large number of functional mutants of yeast alcohol dehydrogenase, in which the properties of this enzyme have been altered in specific ways. In collaboration with Professor Hans Jornvall, who has sequenced the wild-type molecule, we will determine the amino acid substitutions responsible for such varied changes as alterations in the binding constants and in the cooperativity between subunits of the molecule. The technique for producing the mutants involves the discovery that respiratorily incompetent ("petite") yeast requires alcohol dehydrogenase activity in order to survive; selecting cells in the presence of molecules that interact specifically with the enzyme results in mutants in which the structural gene is changed. The advantages of our system over those being pursued in other laboratories are that we are able to look at functions other than the catalytic one, and that yeast alcohol dehydrogenase is a very well-studied enzyme in which the primary sequence is known. This work should lead to a fuller understanding of enzyme function. BIBLIOGRAPHIC REFERENCES: Wills, C. and C. Miller. 1976. A computer model allowing maintenance of large amounts of genetic variability in Mendelian populations. II. The balance of forces between linkage and random assortment. Genetics 82:377-399. Wills, C. 1976. Mendelian Population Genetics and Evolution (book review). Evolution 30:198-199.